Process of preparing octadecadiene acid



Patented May 1939 Remmet Priester, Deventer, Netherlands, assignor to Naanilooze Vennootschap Noury & Van Der Lande's Exploitatiemaatschappij, Devonter, Netherlands, a company of the Netherlands No Drawing. Application May 9, 1986,

- Serial No. 78,922 i 17 Claims. (260-413) The present invention relates to the preparation or production of unsaturated fatty acids of the type containing two double bonds and to the preparation of an intermediate product from- 5 which said unsaturated fatty acids may be derived.

More particularly stated, the present invention relates to a process for thepreparation of 9,11- octadecadiene l-acid from ricinoleic acid, accord- 10 ing to which process it is possible to very efllciently and effectively convert ricinoleic acid into 9,1l-octadecadiene l-acid and to obtain the practically pure 9,11-octadecadiene l-acid.

The term ricinoleic acid", as used above and 15 inthe following parts of the description and in the claims, is intendedto embrace pure ricinoleic acid, ricinoleic "acid in admixture with other bodies occurring normally in association therewith, fatty acids obtained from castor oil and no known as castor oil fatty acids, which castor oil fatty acidscomprise ricinoleic acid, as well as ricinoleic acid derived from any source or produced by any method of preparation.

The castor oil fatty acids to be used in the u process of the presentinvention, may be produced by the splitting up of castor oil. It is immaterial, whether the splitting is effected by means ,of alkalies, the so-called Twitchells reagent, or of a ferment or by another method.

so The technical product known as castor oil fatty acids may contain a certain percentage of unsplit oil; moreover, by the heating involved in the splitting process, chemically bound water may be driven out from the castor oil or from the castor 35 oil fatty acids. It is to be understood, that the products formed in these various reactions may be present in the starting, material to be used for preparing 9,1l-octadecadiene l-acidaccording to the process of the invention. Further- 4 more it is possible to subject castor oil to a heating process, e. g. at a temperature of 200 to 300 C. with orwithout a catalyst, by which heat-- ing process a certain amount of chemically bound water is driven out, to split the product thus 45 obtained e. g. by means of alkalies or by another method, and to usethe fatty acids manufactured in this way in the process of the invention. All

of these forms of castor oil fatty acid are in tended to be included in the terms '"ricinoleic 50 acid used in the'appended claims.

According to the present invention ricinoleic acid is subjected to a heating operation. In its simplest form this heating operation consists in heating ricinoleic acid at a temperature of above 270 C. for a period oftime long enough to con- 5 vert it into 9,11-octadec'adiene1-acid. I prefer to perform this heating operation at atemperature oi 290-31? 0., because better yields and purer products are obtained at these tempera: tures. By heating'ricinoieic acid at the abovementioned temperatures and underreduced pres+ sure, practically pure 9,11-octadecadiene la cid distills from the mass being heated as it is formed -1 and may be condensed in the usual way. Pref.- erably the distillation process is carried out under 1' a pressure not surpassing 30 mm. of .mercury absolute. "L, Y Y 1 I have found, however, that the formation of 9,11-octadecadiene l-acid from ricinoleic acid takes place at a faster, speed and that the 9,11- octadecadiene l-acid is obtained in a still higher degree of purlty, if the above described'heating operation is preceded by another heating process. This treatment prior to the heating operation,

that yields 9, 11-octadecadiene l-acid, is carried out at a temperature below 260 C., for example at 250? C. Thus .in the preferred form of my invention ricinoleic acid is, subjected to two successive regulated heating operations. r

' The way in which these successive heating operations are carried out and the theoretical outlines of the reactions that" are supposed to" take place during the heating processes, will ,be explained in detail in the following lines.

I have found that by the first of these heating operations, two or more molecules of ricinolelc acid'are caused to combine in a manner that a hydroxyl group in the chain of one molecule unites with a hydrogen atomcontained in the carboxyl'group 'of another molecule of rlcinol'eic 40 acid to form a molecule of water. Therefore, as

.a re mm: the first heating operation, water is driven riff as water vapor and the progress of'the reaction can be ascertained by the amount of water which is driven off or by other means, such as, for example, by determining the acetyl and/or acid values. In this first heating operation the ricinoleic acid is converted into a poly acid (polyricinoleicacid) that is to say into an ester acid,

or estolide. The "chemical" reaction involved "in" represented by the following chemical equation:

omwm ongib'iijicmon=jmqnmc00H i (ricinoleic we) I EE i plus o=c(cm)1cn=oncmcn(oa cnmcH,

(ricinoleic acid) equ clmonmcnicHr-0H=cH(cm)1c0on A +H1O 0=c(cm)1cH=cHcmcn(0nxcnmcm Where, in the more usual case, more than two molecules of ricinoleic acid combine, a similar union takes place, and the ester acid or estolide resulting from the reaction of three molecules of ricinoleic acid may be represented as follows:

I 13y maintaining the temperature during this first temperature indicated; and the conversion occurs substantially without decomposition of the ester acid or estolide to form 9,11-oc'tadecadiene l-acid. Preferably a conversion temperature not exceeding 250 C. is employed in the first heating operation. As indicated above, the formation of the ester acid or estolide is accompanied by the formation of water, which, under the temperature employed, escapes as steam or water vapor from the mass being heated. Temperatures below 250 C. may be employed, for example, temperatures from 150 CftO 250 0., however, with temperatures' lower than 250 0., the formation of the ester acid or estolide is slower and not so complete.

Besides the formation of'estolide, as described in the preceding lines, other reactions maytahe place to a certain extent during the heating process. E. g. it may be, that in small amounts socalled lactones are formed, having by way of example the following formula:

In the formation of these lactones from ricinoleic acidwaterisalsosplitoifr The ester acid or estolide resulting fromthe first heating operation, either with or without prior cooling, is next-subjected to a second heata temperature above 2702 0., for example, at

temperatures between 270 C. and 350 0., but

the second heating. operation is preferably conducted at a temperature of about 290-315 0.

However, temperatures above 320 Q. usually produce undesired polymerisation and decomposi- -this production of ester acid or estolide may be tions. The range of 290-315 C. is very effective in converting the ester acid'or estolide into 9,11-

octadecadiene i-acid, since at that temperature veryexcellent yields of the 9,11-octadecadiene .l-acid are obtained, the losses due to undesired polymerization in'the heating zone are low, and the 9,11-octadecadiene l-acid may be distilled from ,the mass being heated as it is formed, practically pure and substantially free of ricinoleic acid and ester acid or estolide. The chemical reaction according to which the ester acid or estolide yields 9,11-octadecadiene l-acid may be represented in the following manner:

9,11-octadecadiene l-acid.

By first forming the ester acid or estolide under controlled temperature conditions and subsequently decom sing the ester acid or estolide also under con rolled temperature conditions, it has been found that very pure and large yields of 9,11-octadecadiene i-acid are attainable, so that this embodiment of the present invention affords a convenient method of preparing 9,11-

tioned above the temperature on an operating 0 basis does not considerably exceed 250 the temperature, during the second heating operation is maintained above 270 C., it i s,to be understood that some small variations in these temperatures are permissible, considering that the temperature of 250 C. differs only by 20 from the temperature of 270. and that that difference in temperature approximately represents the difierence between formation of ester acid or estolide on the one hand and 9,11-octadecadiene 1-acid.on the other. That. is to say, although these specific operating temperatures are described, they may vary more or less on one side or the other of the'points given, provided that in the first heating step there is effective conversion of ricinoleic acid into a body for the r C., and

most part consisting of ester acid or estolide and that the temperature in the second heating operation is suificient to decompose the ester acid or estolide into 9,11-octadecadiene l-acid. From the foregoing it'is ohvious'that the temperature in the second. heating operation must not exceed the decomposition temperature of 9,1 1 octadecadiene l-acid. The purity of the 9,11-octadecadiene l-acid as well as the percentages of yields thereof depend considerably-on maintaining the .temperature used in forming the ester acid, or estolide in the first heating operation as far removed as practical from the temperature of conversion of ester acid or estolide to 9,11-octadecadiene l-acid. a 'The first heating operation described above, by which ricinoleic acid is converted-into an ester acid or estolide, may be conducted at atmospheric pressure, or super-atmospheric pressure, or

s ears? millimeters of mercury, and preferably at 10 millimeters of mercury absolute.- The so called cathodic vacuum may be employed, if desired. Water vapor, benzol vapor, carbon dioxide, other inert vapor or gas, preferably steam, is passed through the material being heated in the second heating operation, to accelerate the carrying over of the vapors of 9,11-octadecadiene l-acid to the condenser for the latter.

It is to be understood, that the temperature at which the estolide has to be heated in the distillation process, depends within the limits stated above to a certain degree on the pressure, under which the distillation is being carried out. The lower the pressure under which the distillation is taking place, the lower the distillation temperature may be. However, it is necessary to maintain the limits for the distillation temperature given above. The speed of distillation has to be such, that the decomposition of -the estolide into the 9,11-octadecadiene l-acid has suflicient time for taking place. In general, a rather low speed of distillation is desirable, in order to avoid the formation of by-products, that diminish the degree of purity of the.9,11-octadecadiene l -acid, obtained in the process. If necessary the 9,11- octadecadiene l-acid, obtained in the first distillation process, may be subjected to a second distilling and fractionating operation at reduced pressure in order to enhance the degree of purity. This second and, if necessary, following distilling operations may be carried out at a lower temperature than the first one, e. g. at the normal distillation temperature of the higher fatty acids. It stands to reason that this temperature may vary considerably according to the pressure under which the distillation is carried out. The lower this pressure, the lower the distillation temperature may be.

Although theoretically the distillation process maybe carried out without obtaining any residue, all the ricinoleic acid present being finally con.- verted into 9,1l-octadecadiene l-acid, in practice some residue is always left in the still. It may even be practicable to continue the distilling process, until the residue is still fairly high, because in this case the residue has useful properties, so that it may be utilized for special purposes. If e. g. the distillation process is continued until the residue is 30-20% of the original weight of the-castor oil acid, the residue will be stilla liquid, and maybe esterified eg. with glycerol or with another aliphatic polyli'ydric alcohol or with a mono alcohol, togive a product, that may be used in the manufacture of varnishes and the like. I

- j The vessel in which the first heating operation described above is conducted may be connected at or near its bottom with a pipe which leads into a second heating vssel in which the second heating operation may be conducted, so that the product from theflrst-heating stage can either be continuously or intermittently fed, by gravity, by suction or by pumping into the second heating stage. The heating vessel in which the second heating operation described above"is performed is necessarily equipped with means to produce the reduced-pressure desired and with condenser means for condensing the 9,11-octadecadiene 1- acid which distills over during the second heating pperation. The condensed 9,11-octadecadiene l-acid is practically pure, being substantially free of ricinoleic acid, esters of ricinoleic acid and estolide. If necessary, it may be redistilled and refractionated at reduced pressure, as described above, in order to still further the degree of purity. a

As pointed out by the embodiment of my process in which ricinoleic acid is subjected to two successive heating operations, it produces a purer product and gives better yields than the simpler form in which only one heating operation is applied. To a certain extent the yields of 9,11-

octadecadiene l-acid obtained and the degree of purity of this product depend on the duration of the first heating operation.

When the object in view is to obtain very efficient and large percentage yields of pure or relatively pure 9,11-octadecadiene l-acid, the heating in the first heating operation, described above is conducted for a long enough period of time to convert the ricinoleic acid mostly or completely to the ester acid or estolide of ricinoleic acid: but if the purity of the.9,11-octadecadiene l-acid or its percentage of yield is not an essential requirement, the heating in the first heating operationmay be conducted for any desired period of time depending upon yields of ester acid or estolide, or 9,11-octadecadiene I-acid. that are enhance desired. The temperature and time of heating during the first heating operation are preferably respectively high and long enough to form estr acids or estolides of very high molecular weight; that is to say to cause the union of many molecules of ricinoleic acid in a chain by the hydroxyl group of one molecule combining with the carb'oxyi group of another, so that tetra-, penta-, hexaand higher polyricinoleic acids or polyestolides are formed, according to the duration of the heating. This degree of condensation can be controlled and estimated by determining the acetyl or acid numbers or the quantity of water split off. The more the condensation has'progressed, the lower will be the acetyl and acid numbers, while the quantity of water split off will be larger.

. 1 According .tothe present invention ester acids or estolides can be produced with practically zero acetyl number or value and of an acid number as low as 20. By suitably prolonging the heating in the first heating operation, ester acids or estolides having acid numbers lower than 50 and even lower than 30 can be obtained. The heating can be continued to bring down the acid number to 20, depending on the composition of the castor oil fatty acid. These ester acids or estolides are thick viscous liquids at room temperature (20- 25 C.) and are particularly useful in the preparation of 9,l 1-octadecadiene l-acid as herein described. A product produced from rlcinoleic acid,

according to the present invention, by heating in the absence of'catalyst, for about eight hours a March 27, 1936.

allowed to cool or the said mass may be cooled by cooling coils, and the above described second heating operation omitted, whereby a product consisting essentially of ester acid or estolide is obtained. Such a product may be used and sold as a. distinct product, and the said product may be used as a means of providing 9,11-octadecadiene l-acid in a reaction progressing at a tem-' perature high enough to bring about its conversion into 9,1l-octadecadiene l-acid.

The 9,1l-octadecadiene l-acid produced by this process can be used for reaction with glycerol and phthalic anhydrid to form a resin, e. g., a normal glyptal resin. A process for making resins off this type with the aid of 9,11-octadecadiene l-acid is described in my copending application, Serial No. 78,923, ot-even date and relating to: Synthetic resins and methods for making the same. The estolide can be similarly used, or mixtures of the estolide with the 9,11- octadecadiene l-acid, and/or other fatt acids, This process for making resins is desc ibed in my copending application Serial No. 71,316, dated It is also possible to use mixtures of 9,11- octadeca'diene l-acid, produced by my process, and other fatty acids derived from drying, semi-' drying or non-drying oils, in the manufacture of resins. It is to be understood, that the use of 'all' these products is not restricted to the so called glyptal resins, but that they may be utilized also 4 for the preparation of other types of resin, in whigh normally fatty acids or estolides are being use The 9,11-octadecadiene l-acid or the estolide canalso be used to produce the mono-, dior triglycerides or similar esters with other polyhydric alcohols. These products can be used in making resins with polycarboxylic acids or anhydrids thereof, e. g. phthalic acid or its anhydrid.

It is also possible to use the products in question for other purposes, e. g. in making varnishes, lacquers and in general all products, for which linseed oil, wood oil and similar oils are usable.

The 9,11-octadecadiene l-acid or the estolide or the esters of these products with glycerol or other polyhydric alcohols may be subjected to known processes, such as polymerization (bodying), oxidation (blowing), treatment with chlorine, sulphur, sulphur chloride, etc. Furthermore they may be siccativated with compounds of cobalt, manganese and other metals. These processes are carried out in a similar way as in the ease of linseed oil, wood oil or similar oils or of the corresponding fatty acids.

- By the term "estolide" used in the appended claims, I intend to include the compounds usually designated as estolides as well as compounds having the same formula as estolides except that the carboxyl group at one end of the chain of the estolide molecule has combined with the hydroxyl group at the other end of the chain with the formation of water, as well as mixtures of estolides and said last mentioned compounds, the said last mentioned compounds being produced, for example, at least at some of the temperatures lying within the range of 150 to 260 C., inclusive, at

. which temperatures ricinoleic acid, according to "7,6 to a temperature of 200-315 C.

2. The process of preparing 9,1l-octadecadiene l-acid which comprises subjecting ricinoleic acid to'heating ata temperature between 150 to 250 C., inclusive, effective to convert the same to ester acid or estolide, the said heating being performed until the material being heated has an acid number not exceeding 50, and thereafter converting the latter material to 9,11-octadecadiene l-acid by subjecting it to a temperature of 290-315 C.

3. The process of preparing 9,11-octadecadiene l-acid which comprises subjecting ricinoleic acid to a temperature between 150 to 260 C., inclusive, the said temperature being applied until the material so treated has an acid number not exceeding 50, and thereafter subjecting the said last mentioned material to distillation at reduced pressure at a temperature above 270 C. but below the decomposition temperature of 9,11-octadecadiene l-acid, whereby 9,11-octadecadiene I-acid is obtained as a distillate. J

' 4. The process of preparing 9,11-octadecadiene l-acid which comprises subjecting ricinoleic acid to a temperature between 150 and 250 C., inclusive, effective to form ester acid or estolide, the said temperature *being applied until the material so treated has an acid number not exceeding 50, and thereafter subjecting the said last mentioned material to distillation at reduced pressure ata temperature of 290-315 C. whereby ll-octadecadiene l-acid is obtained as a distilla e.

5. The process of preparing 9,11-octadecadiene l-acid which comprises subjecting ricinoleic acid from ricinoleic acid. 7. As an intermediate product suitable for the preparation of 9,11-octadecadiene l-acid, an estolide of ricinoleic acid, substantially free from unconverted ricinoleic acid, the same being a viscous liquid at room temperature, and which has an acid number below 30, said product yielding substantially pure 9,11-octadecadiene l-acid by heating above 270 C. 8. Processfor producing 9,11-octadecadiene 1- acid which comprises heating ricinoleic acid at a temperature not exceeding 260 C. effective to form an estolide of ricinoleic acid, said heating being continued at least until it is converted into a body for the most part consisting of an estolide of ricinoleic acid, and thereafter, heating said body at a temperature above 270 C., but below the temperature at which 9,'1l-octadecadiene 1- acid decomposes, to form 9,11-octadecadiene 1- acid. I v

9. Pro essfor producing 9,l1-octadecadiene 1- acid w ch comprises heating ricinoleic acid at a temperature not exceeding 260 C. until it has an acid number below 50, and thereafter heating it under reduced pressure ata temperature in excess of 270 C., but below the temperature at which 9,1l-octadecadiene l-acid decomposes.

10. Process for producing 9,1l-octadecadiene 1- aware? acid which comprises heating to a temperature in excess of- 270 C.,- but below the temperature at which 9,11-octadecadiene I-acid decomposes, a

. body consisting at least for themost part of an ester acid or estolide or ricinoleic acid. v i

11. Process for producing 9,11-octadecadiene ivacid which comprises heating to a temperature in excess of 270 C., but below the temperature at which 9,11-octadecadi ene 1- acid decomposes, the estolide product obtained by heating ricinoleic acid, at a temperature not exceeding 260 C. effective to produce the ester acid or estolide of ricinoleic acid, until the said product has an acid number below 50.

12. Process for producing 9,11- ctadecadiene 1- acid which comprises heating to a temperature in excess of 270 C., but below the temperature at which 9,11-octadecadiene l-acid decomposes, the estolide product obtainedby heating ricinoleic acid at a temperature not exceeding 260 C. effective to produce ester acid or estolide of ricinoleic acid until the acid number of said product is lower than 30.

13. Process for preparing 9,11-octadecadiene 1- acid which comprises subjecting ricinoleic acid' to a temperature between 150 to 260 C., inclusive, in the presence of an esterification catalyst effective in causing the conversion of ricinoleic acid to an ester acid or estolide, said temperature being applied until the material so treated has an acid number not exceeding 50, and thereafter subjecting the said last mentioned material to a temperature above 270 C., but'below the decomposition temperature of 9,11 -octadecadiene 1- aeid, to form 9,1 1-octadecadiene i-acid from said material. a a

a temperature not exceeding 260 C. until it is converted into an estolide resulting from the union of at least four molecules of ricinoleic acid,

and heating said material at a temperature in excessof 270 C. but below the temperature at which 9,11-octadecadiene l-acid decomposes.

15. Process for treating ricinoleic acid to convert it into an acid of a greater degree oi! unsaturation, said process comprising heating ricinoleic acid at a temperature not exceeding'260" C. effective to form'an estoiide resulting from the union of at least four molecules of ricinoleic acid, said heating being applied until an estolide resulting from the union of at least-four molecules of ricinoleic acid is formed, and heating said material at a temperature in excess of 270p. but below the temperature'at which 9,11-octadecadiene i-acid decomposes.

16. Process for preparing 9,11-octadecadiene 1- 'acid which comprises heating, at a temperature above 270 C., but below the temperature at which said acid decomposes, an estolide resulting from the union of at least four molecules of ricinoleic acid.

- 17. Process for preparing an acid of a' greater degree of unsaturation than ricinoleic acid, which process comprises heating, at a temperature above 270 C., but below the temperature at which 9,11-

14. Process ior preparing 9,11-octadecadiene 1-. acid which comprises heating ricinoleic acid at octade'cadiene 1- acid decomposes, anestolide resulting from the union of at least four molecules,

of ricinoleic acid.

. REMME'I' PRIESTER. 

